Copper melting furnace method



June 20, 1933.

R. P. HEUER COPPER MELTING FURNACE METHOD June 20, 1933. R. P. HEUER COPPER MELTING FURNACE METHOD Original Filed April 23, 1930` 5 Sheets-Slfleell 2 June 2o, 1933. R, P, HEUR 1,914,717

GQRPER MELTING FURNAGE METHOD Original Filed April 25, 1930 5 Sheets-Shea?I (5 raamt@ im@ ao, ieee j anar/ir .'RSSELL PEAR/SE EEUM, @F EAVJERFDRD, PENNSYLVANILA, .SSZGNR 'E0 TEE AMMICAN METAL @@MPN LMIITED, 0F NEW YQBK, lil'. Y., A COEPURATEON Yoan original appagante una anni au, ieee,

My invention relates to continuous copper melting furnaces,

@ne purpose of my, invention is to eliminate A further purpose is to control the rate of i preheating within a preheater attached to a Vmelting furnace, variantly using heat from the hot products of combustion from the melting furnace to preheat combustion air for the melting furnace, so as toJ alter the capacity of the melting furnace to melt. the charges, and in correspondingly varying the rate of feed ci thefcharges through the preheated paths.

- A further purpose is to use a melting furi nace with a preheater and'to control operation of the furnace by the operation of the preheater and vice versa. p l

A further purpose is to automatically 1ncrease the heating of a melting furnace when the preheater is receiving an excess amount of heat so as to handle the charges in the furnace at a more rapid' rate and thus equalize the preheating and melting furnace operations. Y

A further purpose in conjunction with a melting furnace is controllablyvto preheat combustion air for the furnace burner and metallic charges to be melted, so that with increase of heating of the charges additional preheat-ing of the air to a burner may be made to increase the intensity of furnace heat-ing and thus melt the charges at greater speed.

A further purpose in the embodiment shown is to rovide a bypass for the preheatin gases rom a melting furnace and to utilize the temperature of the gases in the bypass as a means for equalizing the relative Serial No. 446,504. Divided and this application lerl March 23, m33.. Serial No. 524,452.

melting in the furnace and heating in the preheater.

Further purposes will appear in the specilication and in the claims.7

My invention relates to the vmethods involved and also to apparatus by which these methods may be carried out.

The present application is a division of I I copending application, Serial No. 446,504, Copper melting furnace, tiled April 23, i930.

My invention is applied to furnaces for preliminarily heating copper by the hotl products of combustion Afrom a reverberatory urnace used for melting copper and in which the operation of the urnaceis intended to be continuous @ne illustration ot the general character of furnace to which the invention is applied is shown in a patent to Lulrens and Heuer,

No. l,733,4ll9 or @ctober 29, 1929, in which the copper charges are shoved down a sloping Hue and are dropped from the lower end or the due into the molten metal pool and in which the hot products ot combustion pass upwardly through the same due to the staclr,

the same/time well illustrates the principles of my invention.

Figure 1 is a horizontal section taken upon the line 1--1 of a furnace embodying my invention and seen .in Figure 2.

Figure 2 is a section -upon line 2-2 of Figure 1. y,

Figure 3 is an enlarged, fragmentary, vertical-section upon line 3--3 of Figure l1.

Figure 4 is a fragmentary section taken i vupon line 4.4 in Figure 1.

In the drawings similar numerals indicate like parts. Y

The furnace 10 is intended to be a conventional reverberatory furnace heated by any suitable means such as by the flame 11 from a liquid or gaseous fuel or powdered coal burner 12 whose hot products of combustion pass above the molten copper pool 13 4and are ultimately discharged from the stack 14. Between the furnace and the stack these products pass through a iue 15, in adirection which is selected as counterclockwise in Figure 1, from the point of iiue entry 16 to the point of stack discharge 17. The direction is,

i of course, immaterial.

`The flue 15 need not have any slope and, as shown in the drawings, is horizontal so as to receive charges at some kpoint 18 and to heat them while they are being carried in a direction counter to that of the flue gases from the point 18 to a point of discharge 19.

I am careful not to melt the 'charges within the flue, and I plunge them beneath the molten surface of the bath while this molten surface is protected by a coating 20 of slag.

The liue 15 is desirably circularly annular in horizontal section, but whatever its shape, a-support and guide, such as the track 21, is provided upon which a hearth 22 (continuous or discontinuous) is progressed so that the hearth may load at 18 and discharge at 19 in continuous progression about the track.

Though the detail of the structure is immaterial to the broader aspects of my invention, under the requirements of the. statute I have given, and will give, considerable detail in explanation of the best embodiment of my invention shown in the figures.

At the loading point 18 I show in Figure 4 a plunger conveyor 23 having a rack 24 driven by a gear 25 and having roller supports above and below the. plunger at 26. The conveyor operates within a loading chamber 27 protected against gas discharge by a movable cover 28 soy that when the cover is lifted a charge 29 may be placed in the line of movement of the conveyor.

In normal copper metallurgy it is necessary to melt blister copper, which is cast into anodes for electrolytic refining. lThese are refined into cathodes which are ultimately ca'st into the marketable forms of copper. Without requiring this, it will be assumed that the charges comprise these cathodes.

The space within the loading chamber is normally protected from the gases of the furnace by asliding door 30 counterweighted at 31. This door is kept closed during the initial loading operation. When the charges have been placed within the chamber 27 and the door 30 has been opened, the plunger is operated to move the charges into the flue to a position corresponding closely with that of the pile of charges 32. These charges are then lifted above the end of the conveyor by elevator arms 33` 34, the conveyor plunger is withdrawn and the charges are lowered upon surface 35 of the hearth, after which the elevatorarms are still further lowered to clear the charges from them and permit movement of the charges along the movement of the hearth.

The upper surface of the conveyor is provided with spaced grooves 36, 37 into which either the charging or discharging plunger may slide.

The elevator arms 33, 34 are lifted and are permitted to lower by cams 38 upon shaft 39 turned by any suitable gearing of which spur gear 40 alone is shown.

The hearth is then move'd from its receiving position in Figure 3 to the `position for discharge into the pool which is shown in Figure 2. In this latter position the charges are in line with any suitable discharge mechanism, here shown as a machine-operated fork 41.

Mechanismpby which a fork vis supported and operated is well known in the art. One well known form is partially illustrated and is not further illustrated here for the reason only that such illustration is unnecessary in view both of the fact that such mechanism is so Well known and of the further fact that the functions can be performed by hand. With a particular mechanism partly here shown the charge is lifted out to clear the bridge wall. The fork is shifted mechanically from its inactive dotted position at the right of -Figure 2 to a point where its charge-supporting end 41 lies within one of the recesses 36 (Figures 3 and 4). rll`he fork is then raised so as to clear the bridge 43 and is projected further forward through the dotted position at the left of Figure 2 to a position over the pool, at which the plunger 42 is advanced by means of the rod 42 to discharge the pile of cathodes into the pool. Because the cathodes fall from a height they plunge beneath the slag surface of the pool.

The opening 44 for passage of the fork is protected against intrusion of the products of combustion by a door 45 which is opened for each discharge of a pile of c'athodes.

One advantage of making the flue horizontal is that the track may be made continuous about the iue, permitting movement of the hearth in the same direction to successive positions of loading and discharging, with the disadvantage, however, that it becomes then highly desirable to reduce the short-circuiting of hot products of combustion from the furnace to the flue in a direction which in Figure 1 would be clockwise. This can be effected sutliciently for the purpose by the use of a partition 46 which permits the hearth to pass through but closes the greater part of the flue space.

For a purpose hereinafter explained the partition 46 does npt in itself wholly cut off the short-circuiting flow of gases to the flue.

tere-air A passage 47 is provided byvvhich partial gas tlovv may be permitted ,'f the extent ot this lioW can be controlled or the idovv can be stopped entirely by the use oi the valve or damper 48. y

Because the partition 4t is located at a' point Where the hearth or carrier is empty, it can be confined closely to the level or the emptyhearth, leaving but very small space for possible leakage ot products of combustion, which are cut on at the bottornwby the sand seal.

The hearth is protected against leakage of flue gases downwardly by a sand seal 49 carried by the hearth in any suitable vvay, as by bracket 48, and Within which alixed sealing edge 49 engages.

@cors l5 are placed in the refractory Walls of the due l5 to make the interior accessible :tor repair.

Under normal operation oit the furnace it is contemplated that hot products of combustion shall all or substantially all pass through the horizontal llue l5 tothe stack, and shall all or substantially all be used for preheating the charges. However, because of variation in the amount of heat required for the turnace, dependent largely upon the rate at which charges are delivered to it, and in the number and speed of preheating of the charges which may be required, l have provided the bypass 47 for part of the hot products of combustion in order that some of themv may be short-circuited to the chimney Without `beratory furnace.

passing about the horizontal conduit l5.

Within the stack ll place a preheater 50 for preheating the inlet vair 54 supplied to the furnace, and connect one header 5l with the burner 12 through a pipe 52 having inlet 53.

rlhe heat for melting the charges is applied Within the preheater and in the reverlt is desirable'that in the division of the heat applied these two places the preheater shall bring the charges up as nearly to melting as possible without danger of any melting in the preheater.

vllior the purpose of securing this result the relative amount ot heating which takes place in the preheater and in the reverberatory heating to take place in the preheater, which` would cause the charges to melt on the pre-l heater hearth and stop the travel of the hearth.l To preventthis some of the excess gases from the reverberatory furnace may be bypassed directly to the exit stack Where they are edective in preheating the air which supports combustion in the reverberatory fur- The increase in the temperature of the combustion air increases the rate of heating Which taires place in the reverberatory `furnace to an extent out ot proportion to the extent ot air heating; and this increased heat in the reverberatory 'furnace will permit a corresponding increase inrate or speed at which the charges are ed through the preheater, which Will still further eliminate the tendency or melting to taire place in the preheater and at the same time will speed up .the

operation ot the furnace.

lln order to control the total amount of Withdrawal of products oi combustion from the reverberatory furnace chamber and thus to avoid an excessive reduction of temperature in it by too much short-circuiting ot theproducts ot combustion, ll show a purely conventional fan 55 Within the stack by which the speed oi gases in the stack can be controlled.

Partial short-circuiting of hot products of combustion may be continuous if required. rlhis not only helps to control the temperature in the preheating part of the llue so that the preheating is not excessive, but provides tor increase of the temperature in the reverberatory lfurnace chamber when needed by supplying additional heat in the chimney to-preheat the air for the burner. All of my illustrations are intended to be largely diagrammatic as any orm otipreheater which will perform the function is suitable for this purpose, just as, for example, any form ot conveyor, loading, and unloading mechanism vvhich will perform the respective function may be used to carry out the broader form ot my invention.

My treatment of the hearth as continuous and circular does not, of course, preclude the use of individual cars, although these would be less desirable in practice, nor require that the path described by the cars shall be circular.

Whatever the character of support tor the charges While traveling Within the horizontal flue and Whatever guides be used, wheels 56 may be used to engage the guides.

While vany suitable means for moving the conveyor may he employed, l illustrate a torni which ll prefer because of its simplicity and convenience. A circular rack 57 is secured tothe hearth iframe. 'llhe teeth onthe rack are engaged by a gear 58v onl a shaft 59 to move the hearth. The shaft 59 is driven by any suitable means, here an eloctric motor 62, through reduction gears 60 and 6l.

Continuity or substantial continuity o the conveyor results in a substantially continuous layer of piles of charges about the entire circula-r flue, givin a long path for heating of the charges 1n the individual piles. F or the reason that operation of the iso ing systemI for causing carriers ory cars to move about it, the length of time the charges are subjected to the heat of the Hue is Wholly proaching their melting point, Where thel demand for copper from the pool is moderate, but who may pass them through .with less time for heating Where the desire for additional speed of melting justifies plung ing them into the pool in a less highly heated condition.

By this invention I secure the same bene- [its of greatly reducing the need for blowing the bath totake out sulphur as in the Lukcns and Heuer Patent No. 1,7 33,419, by .removing sulphur in the preheating operation and by reducin the 'amount of sulphur which the metal a sorbs from the combustion gases during the melting... Solid copper does'not absorb sulphur readily, but molten copper,

if unprotected,'absorbs sulphur with great avidity. I thusalso, as in the case of the l' atent above, avoid the subsequent necessity or removing the oxide produced in the blowing.

' Metal `or slag will be drawn o ff throu h the tapopening 10` desirably consisting pool back into the other chargesior back'into the conveyor system. v 1 y p It will be noted that controllable additional heating of the burner air supply bythe hot products of combustion, affords a means by Whichthis air preheating may be made to balance or equalize the rate of melting of the' charges against the rate of reheating within the preheating part ofthe ue Without refer- -ence to how the; air preheating is accom.-

plished.

, This air heating control may be explained asfollows: i y I Y, Y

When the charge-preheating gases-in the flue become relatively too hot, or-vwhich may i, be merely another Way of stating the matter-when the rate of progress of the charges through the preheater becomes reduced to a Vsuiiicient extent so that the charges become `excessively lpreheated yunder the operating `conditions of the furnace at that time,with

consequent danger of melting, or actual melting of the charges in the preheater, With risk of absorbing sulphur. and clogging the conveyor, it is quite desirable to increase the speed of melting in the melting furnace.

This can be done by utilizing some of the heat available from the preheater to preheat, for example, the'cmbustion air and thereby increase the temperaturein the melting furnace. Conditions will then be relieved from two standpoint-s, by reducing the amount of heat in the preheater, and by increasing the rate at which thelnielting furnace is capable of handling the preheated charges so that these charges can be passed more rapidly through the preheater and may thus be subjected'to the preheating temperature for a shorter time. One Way of heating the combustion air inlet is through bypassing a portion of the gas leaving the melting furnace and using it at some portion of its bypassed pathito preheat the combustion air. A very slight increase of temperature'of the combus tion" air Well justifies thevuse of part of the products of combustion for heating this air.

The-question of particular location of the air pipes to be heated Within the path of these bypassed products of combustion is a matter ofpreference and design and my location of` these air pipes to be preheated Within the stack is not therefore to be considered as even suggesting that this is the only place Where A'they can be'placed. o a refractory gate sovthat the tapping level may 'In view of my invention and disclosure variations and modifications .to meet individ* ual lwhim or particular need will doubtless become evident to others skilled in the art, to

obtain part or allv ofthe benefits of my in- -vention Without copying the structure shown, andal, therefore, claim all such in so far as they .fall within4 the reasonable .spirit and scope of my invention. f

i Having thus .described my invenion, what lI-claim as lPatent iscneW and desire to secure by Letters l. The method of controlling the rate of v roasting and preheating within a roaster and preheater attached to afcopper melting furnace, which consists in variantly using heat lfrom the hot products of combustion from the vmelting furnace to preheat lcombustion air for'the-melting furnace, so as'to alter the action of the melting furnace in melting the charges', and in .concurrently var ing the rate of feedof the charges through t e preheated paths.. V i

l2. The method of balancingv the 'rate of heating the content of a copper reverberatory furnace and copper charges :within a roaster end preheater fed from said. reverberatory furnace, which consists in bypassing from `the preheating flovvy an adjustable part of the hot gases of combustion from the furnace, in utilizing the bypassed gases to preheat the combustion air for the furnace and in varying the-rate of feed of the'roasting and'preheating chargeas'the rate y of heating of the furnace increases. l 'l j v 3. The method of controlling'the temperature fof vvroasting' land preheating within/a to be 'inserted within a copper melting furnace variably delivering hot products of combustion to said chamber, which consists in extracting part of the heat from the hot products of combustion and transmitting it in the form of added heat to the combustion air for lthe melting furnace, thus increasing the rate of melting of the furnace, and in speeding up the rate of travel of the charges through the preheater commensurately with added melting capacity of the furnace.

4. The method of roasting and melting copper charges in a copper furnace, which consists in separating the furnace products of combustion into two parts, in roasting and preheating the incoming copper charges by heat transfer from one. part, in preheating the inlet air to the furnace by heat transfer from vthe other part and in changing the roasting Y and preheating effect upon the charges by Avarying the part of the products of combustion used to preheat the inlet air and by varying the'rate of feed of the charges.

y5. The method of roasting and melting copper charges in a copper furnace, which consists inl separating the furnace -products of combustion into two parts, in roasting and preheating the incoming copper charges by heat transfer from one part, Iin preheating the inlet 'air to the furnace by heat transfer from the other part, in regulating the volume ofthe products of combustion used in preheating the charges so that the charges will bev delivered to the furnace properly roasted and just below their melting point and in varying the rate of delivery of charges to the furnace as the melting rate changes with change in the temperature of the inlet air.

6. The method of control in roasting 'and e melting copper chargesy in aereverberatory copper furnace having a flue for preheating and roasting charges passing to the furnace,

and a by-pass forl diverting. furnace gases from the flue, which consists in preheating the inlet air to the furnace by the heat from the gases diverted through the by-pass, in varying the speed of progressionof the charges through the flue and in changing the rate of gas discharge through the by-pass, so that the relation of the extentof 'roasting and `the temperature of preheating of the vcharges to the rate of melting of the charges may be regulated, iirst: by changing the speed of '.progression; in which case either the charges will move faster through the flue and will be fed faster into the reverberatory furnace,

having a shorter roasting period at lower temperature, less heat being added during preheating and more heat being absorbed in the reverberatory furnace; or the charges will move slower through the flue and will be fed slower into the reverberatory furnace, having a longer roasting period at higher temperature, more heat being added to the charges during preheating and less heat being absorbed in the reverberatory furnace, and second: b changing the rate of gas dlversion through the by-pass; in which case elther less gas will iow through the flue in Contact with the charges and more gas will be d1- verted through the by-pass, roasting the charges less completely, adding less heat to the charges during preheating and adding more heat to the reverberatory furnace by means of the inlet air; or more gas will flow through the flue in contact with the charges and less gas will be diverted through the bypass, roasting the charges more completely, adding more heat to the charges durlng preheating and adding less heat to the reverberatory furnace by means of the inlet air.

' RUSSELL PEARCE HEUER. 

